These 50/50 raffles started in Canada and are common in Canadian rinks in every community, and they are becoming more common in the USA.

Essentially, you buy as many $1 tickets as you want. Half the total money raised in raffle ticket sales is awarded as a prize in the third period to the lucky ticket holder selected in a drawing, while the other half of the money pot is kept by the organizer, in this case, the Denver Hockey Alumni Association. On Saturday, the winner won about $700, and DUHA got about $700, hence the 50/50 name.